The present invention relates to cleaning devices for heat exchangers and more particularly to a heat exchanger exchange-tube cleaning lance positioning system that includes a three axis cleaning lance positioning mechanism that is attachable to the end of a heat exchanger and that is controlled by a lance position computer controller that determines the location of each of the openings of the exchange-tubes of the heat exchanger by analyzing an image signal generated by a camera mounted to the three axis cleaning lance positioning mechanism and then positions a connected exchange tube cleaning lance into and through each of the exchange-tube passageways to clean the exchange-tube passageways automatically.
Heat exchangers are used extensively in manufacturing plants to maintain process control over various manufacturing processes such as in the production of plastics and other chemicals. Although these heat exchangers allow the plant to operate, they contain exchange-tubes through which the manufactured chemicals must flow that often become narrowed by the accumulation of the chemicals on the inner walls of the exchange-tubes. This narrowing causes inefficient heat exchange to occur and can reduce plant production. To counter this narrowing build up, work crews must typically, at least partially disassemble the plant in order to move the heat exchanger to a location where a work crew can then manually position a high pressure cleaning lance through each of the exchange-tubes to remove the narrowing build up. Cleaning the exchange-tubes manually with a high pressure cleaning lance is dangerous to the workers because the cleaning lance generates high pressure jets of water that can easily injure a worker and the narrowing buildup removed by the high pressure jets can include dangerous chemicals that can poison and/or chemically burn the skin, lungs, eyes and other body parts of the workers on the work crew. In addition, manual cleaning of the exchange-tubes with a high pressure cleaning lance is slow, physically exhausting and expensive to perform. It would be desirable, therefore, to have a portable lance positioning system which could be attached to an in place heat exchanger thereby eliminating the need for moving the heat exchanger to a cleaning location. It would be a further benefit to have a lance positioning system that would also automatically position the cleaning lance through each of the exchange-tubes to clean the tubes rapidly, with fewer men and without the physical exertion now required by current lancing techniques.
It is thus an object of the invention to provide a heat exchanger exchange-tube cleaning lance positioning system that includes a three-axis cleaning lance positioning mechanism; a camera mounted to the three axis cleaning lance positioning mechanism; and a lance position computer controller in image signal receiving connection with the camera and in controlling connection with the three-axis cleaning lance positioning mechanism, the lance position computer including a user control interface; the three-axis cleaning lance positioning mechanism including a heat exchanger head flange connecting mechanism for rigidly attaching a non-moving portion of the three-axis cleaning lance positioning mechanism to the heat exchanger head flange of a heat exchanger; a lance depth drive mechanism having a lance connecting structure for connecting an exchange-tube cleaning lance thereto and a lance positioning mechanism for linearly positioning a tip end of a connected exchange tube cleaning lance into and out of an exchange-tube of the heat exchanger when the tip end of a connected exchange tube cleaning lance is positioned in a direct line with a horizontal exchange-tube center coordinate and a vertical exchange-tube center coordinate that corresponds with the flow passageway of the exchange-tube and the front of the open end of the particular exchange-tube; a horizontal lance positioning mechanism in connection with the lance depth drive mechanism in a manner to position a connected exchange tube cleaning lance at a horizontal coordinate corresponding to the horizontal exchange-tube center coordinate for a particular exchange tube; and a vertical lance positioning mechanism in connection with the lance depth drive mechanism in a manner to position a connected exchange tube cleaning lance at a vertical coordinate corresponding to the vertical exchange-tube center coordinate for a particular exchange tube; the lance depth drive mechanism, the horizontal lance positioning mechanism and the vertical lance positioning mechanism all being moveably mechanically connected to the non-moving portion of the three-axis cleaning lance positioning mechanism in a manner such that, when the non-moving portion of the three-axis cleaning lance positioning mechanism is fixedly attached to the heat exchanger head flange, it is possible to position the tip end of a connected exchange tube cleaning lance in a direct line with a separate pair of horizontal and vertical exchange-tube center coordinates that correspond with the flow passageway and the front of the open end of each of the exchange-tubes connected to the tube sheet; the lance position computer controller being programmed to analyze an image signal corresponding to an image of the tube sheet received from the camera after the non-moving portion of the three-axis cleaning lance positioning mechanism is fixedly attached to the heat exchanger head flange in a manner to identify each open end and each flow passageway of each of the exchange-tubes connected to the tube sheet and to calculate and store a separate pair of horizontal and vertical exchange-tube center coordinates relative to the non-moving portion of the three-axis cleaning lance positioning mechanism that correspond with the flow passageway and the front of the open end of each of the exchange-tubes connected to the tube sheet; the lance position computer controller being responsive to input signals from the user control interface in a manner such that the lance position computer controller generates control signals to the lance depth drive mechanism, the horizontal lance positioning mechanism and the vertical lance positioning mechanism of the three-axis cleaning lance positioning mechanism such that a connected exchange tube cleaning lance is positioned into and out of each exchange-tube of the heat exchanger for which a separate pair of horizontal and vertical exchange-tube center coordinates is stored.
Accordingly, a heat exchanger exchange-tube cleaning lance positioning system is provided. The heat exchanger exchange-tube cleaning lance positioning system includes a three-axis cleaning lance positioning mechanism; a camera mounted to the three axis cleaning lance positioning mechanism; and a lance position computer controller in image signal receiving connection with the camera and in controlling connection with the three-axis cleaning lance positioning mechanism, the lance position computer including a user control interface; the three-axis cleaning lance positioning mechanism including a heat exchanger head flange connecting mechanism for rigidly attaching a non-moving portion of the three-axis cleaning lance positioning mechanism to the heat exchanger head flange of a heat exchanger; a lance depth drive mechanism having a lance connecting structure for connecting an exchange-tube cleaning lance thereto and a lance positioning mechanism for linearly positioning a tip end of a connected exchange tube cleaning lance into and out of an exchange-tube of the heat exchanger when the tip end of a connected exchange tube cleaning lance is positioned in a direct line with a horizontal exchange-tube center coordinate and a vertical exchange-tube center coordinate that corresponds with the flow passageway of the exchange-tube and the front of the open end of the particular exchange-tube; a horizontal lance positioning mechanism in connection with the lance depth drive mechanism in a manner to position a connected exchange tube cleaning lance at a horizontal coordinate corresponding to the horizontal exchange-tube center coordinate for a particular exchange tube; and a vertical lance positioning mechanism in connection with the lance depth drive mechanism in a manner to position a connected exchange tube cleaning lance at a vertical coordinate corresponding to the vertical exchange-tube center coordinate for a particular exchange tube; the lance depth drive mechanism, the horizontal lance positioning mechanism and the vertical lance positioning mechanism all being moveably mechanically connected to the non-moving portion of the three-axis cleaning lance positioning mechanism in a manner such that, when the non-moving portion of the three-axis cleaning lance positioning mechanism is fixedly attached to the heat exchanger head flange, it is possible to position the tip end of a connected exchange tube cleaning lance in a direct line with a separate pair of horizontal and vertical exchange-tube center coordinates that correspond with the flow passageway and the front of the open end of each of the exchange-tubes connected to the tube sheet; the lance position computer controller being programmed to analyze an image signal corresponding to an image of the tube sheet received from the camera after the non-moving portion of the three-axis cleaning lance positioning mechanism is fixedly attached to the heat exchanger head flange in a manner to identify each open end and each flow passageway of each of the exchange-tubes connected to the tube sheet and to calculate and store a separate pair of horizontal and vertical exchange-tube center coordinates relative to the non-moving portion of the three-axis cleaning lance positioning mechanism that correspond with the flow passageway and the front of the open end of each of the exchange-tubes connected to the tube sheet; the lance position computer controller being responsive to input signals from the user control interface in a manner such that the lance position computer controller generates control signals to the lance depth drive mechanism, the horizontal lance positioning mechanism and the vertical lance positioning mechanism of the three-axis cleaning lance positioning mechanism such that a connected exchange tube cleaning lance is positioned into and out of each exchange-tube of the heat exchanger for which a separate pair of horizontal and vertical exchange-tube center coordinates is stored.
In one preferred embodiment, the lance position computer controller generates control signals to the lance depth drive mechanism such that the connected cleaning lance moves inward in steps consisting of an outward portion and an inward portion; the inward portion being of a greater linear length than the outward portion.
In another preferred embodiment, the lance depth drive mechanism includes a force resistance sensor in connection with the lance position computer controller; and the lance position computer controller monitors a resistance signal from the force resistance sensor, stops the inward movement of the connected cleaning lance when the resistance signal from the force resistance sensor reaches a predetermined threshold value that indicates that the exchange-tube currently being cleaned has an unremovable clog, and completely withdraws the connected cleaning lance, and generates signals to the three-axis cleaning lance positioning mechanism to move the connected cleaning lance to the exchange tube corresponding to the next stored pair of horizontal and vertical exchange-tube center coordinates.